Method and apparatus for making chemical solutions



Oct. 13, 1931. 'r. 1.. DUNBAR 1,826,753

METHOD AND APPARATUS FOR MAKING CHEMICAL SOLUTIONS Filed Feb. 5, 1929 2Sheets-Sheet 1 60 Water Inlet I Gas Outlet A L g a 1% a 6 f2 1 3 9 g 4 14 a i r/ v v/ A1 '7 a. a H01 637w 1.0 Dvgealer or a 4: E I AccumulatorInlet 4.9 a 7 Cooler 1 V 6 Pump \Suqaher Dioxic Y my GasInZet .LzguzdOuiCeZ 4,5 7 a I 5 r wuento'o Z/ A TLDunbar;

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Oct. 13, 1931. T. DUNBAR 1,326,753

METHOD AND APPARATUS FOR MAKING CHEMICAL SOLUTIONS Filed Feb. 5. 1929 2Sheets-Sheet 2 a in g r 'IIIIIIIIIIIIGJL'ILZ'I"; I 4

11,111", (II I!!! Ill ,v, seems reommis DUE-BAR; E wii'rnn l atentedQcti13, 1931 rR-ooEss, EEGOBPORATED, A ooeroimriorror vnw'YoRK neuron ANSAPPARATUS For: rmxme eisrmrcersoreness Applicat-ron meeretruary 5, 1929;Serial 1\To.'337,'",599.

This invention pertains to improvements in; the melting otchemicalsolutions and to new anctusefiii apparatus therefor" Ina specificillustrative embodiment, this invention provides improvements in themanner preparing acid or bisul'phite liquor; for

7 example, suitable for the'digestion of. wood pulp; Also, thisinventi-on prov des improvements towers to!" the. preparation of 1 3such solutions-.1 I

Heretofere, it has. been customary in the ahsorptioniof gases, toproduce-acid solutions, toprovide rel'atiyelsy large absorptionitowersg..ebo.ntninety test invheight, and of substantial diameter, andto. introdncethe' gasesra nd liquids-i-intol jsrichtowers in cold Icondition; and to effect the reactions at about etmosphcrire pressure..-Due to such coiid-it1ons,. 1trequiresrelatively largemasses of 2ohmefor. thehlrs, to provide: thereqnisl-te c011 v tact. area, andfurthermore, as the substances are not heated, a rel tively great timeis re- .QlliBGCl hQQfikCh the dissolying.otthe-lime or the like. V

7 1 have discovered,- thatv it the lime or the hire is, heated, that thedissolying thereoii is accelerated, and conseqnently, a. 2 much smelterand less-expensive apparatus may be employed! in; such: acid isystems-Furthereo'more; I discovered that the heating of .thehine reeh delomite,or any other suitable reacting compound may he 'efiected by ,heat. unitscontained either in the liquid introduced into the ahsorptioi r tower,"or in 5 the gasraslmitted :tosuch towers. For" ex- ,ample it an systemcontainingsnayimprovements isiomployed' 1ncongnnction with digestersusedfor the digestion of'fibronsl material,- such as wood: ch.ips,fhot-,sstrong or -weak acid from the digesters -01" the digesting system may beintroduced into the ebsorptiontower for the purpose of rapidlydissolving" the lime rock, dolomite or the like.

- '5 I111 the'preparationofthesulphnr-dioxide gas, it is commonpractice. to: produce such gas inasnlphur burner, and to-then-pass thesame through coolers before iiitroclncing the gas EH10 theabsoritiongtowerfl I havegalso found that if snchgas isnot passed throughtrolled. It} is another object of th 'tion' to 'aiiordsnch control, andpart1 coolershat isled directly initsheatedifcon to' the 'absorptiontower, that the di on 1 he, n sloontained in the gas may be imparted-tothe l me rock or the like in the tower, so that such reaction materialimay he expeditiously dissolyed when the liqnid contacts therewith. s

It W1 1i therefore stresse mar ue limestone, dolomite or thelike, isheated in any suitable "way, but; .ipreferably by, the

diiced into the tower;

l have also discovered that absorption, in

pherio pressure, and another objec'tfof the vent-ion is to furnish anacid system "in supertmospheric pressure. I

In the absorption ofgases to; produceaci'd which adsorption may'takeplace "underjsuch: 1

oftheobjects oft-he inven i3 l lde 'anacidfprep'aratior system in whihhrthee solutions,it is highly desirable to increglse the Ifacilityjwith which temperatures may hecjo'n cularly at intermediatestages of the absorption process, to obtain reguleblecooling of thebecontrolled from. stageto stage. Yet another object is to stationrelief towers"at.in--

termediatei points in'the' main tower system,

'and in aspecific embodiment, to stationsuch liquid during its progressto a later'stage of I J the absorption. I s M 30 est is to providesuchLinter-f mediate cooling of the absorptionl'iquordiircentrationofithe gasbeing dissolved may" relief towers at regions to which theabsOrpjtion gases may hed i erted after such gases have'been contactedwith" liquid which has passedithro ugh the: intermediate temperatureregulators ai'orementionedc A further objectis to provide such relieftowersras may be regulably interchangeablel jg in effect with anyoneofa' plurality of: absorption zones'ot the tower I s g a An additionalobJeet is to provide means for efficient extraction of the r gases at.the

latter stages of their passage, particularly systemsot th1s;cha-racter,1's faclhtated f the tower 1S maintained undersuper-atmosjust beforethey are vented from the tower system; and also simultaneously by thesame means to condition the liquid that is being introduced into thetower system proper.

Other objects will be apparent with further understanding of thisinvention, and with its practice, as now set forth more in detail.

This invention may be illustrated by reference to the process ofabsorbing sulphur dioxide in water in the presence of an alkalinesubstance. For instance, lime or doloite usually are employed in theproduction of bisulphite liquor, and water and sulphur dioxide gasusually are led countercurrently to each other over the lime containedin towers. In the practice of this invention, there is provided a seriesof such towers, with the improvements to be described placed between twoor more of the stages of the series.

Referring to the drawings, Fig. 1 is a vertical sectional view partly inelevation, of one form of my improved apparock, dolomite, or anyreacting compound or inert filler, to be used in the manufacture of theacid.

A grid or percolation plate 5 is arranged in each chamber to support thetiller 6 through which the liquid percolates into a sump 7 which ispositioned beneath each grid for the accumulation of sludge, etc.

One or more of the chambers is connected I with a supply of hot strongacid or hot gas.

As illustrated in Fig. 1 this fluid flows through a valved pipe 8 from adigester or accumulator, for example, and it is di charged into theupper portion of the chamber 2 by means of a rose or nozzle 10 whichsprays the same uniformly on to the filling 6 of that chamber. herenecessary, a pump 11 may be arranged in the pipe line 8 for forcing thehot strong acid from the chamber 9 to the tower.

. Preferably, the system is of the countercurrent type. and water orweak acid liquor is introduced into the upper chamber 1 through a valvedpipe which terminates in a rose or nozzle 12 that sprays the liquidevenly on to the filler 6 of that chamber. A

gas outlet 13 is also provided for this cham- The lower chamber 3 isfurnished with a valved pipe 14 for introducing SO into that chamber,and this chamber also has a valved pipe 15 serving as a liquor outlet.

16 designates temperature control means or a cooler located between theunits 2 and 3, and liquid from the unit 2 is fed to 16 by way of pipe17. The cooled liquid is discharged from 16 through a pipe 18 thatterminates in a nozzle 18a which sprays the liquid on to the filler 6in. the unit 3. The temperature control or cooler 16 has beenillustrated as conventional coil and tank means.

A valved pipe 19 functions to lead gas from an outlet 20 in unit 3, toan inlet 21 which is locatedin the sump of the unit 1.

In order to pass liquid from the last mentioned sump to the upperportion of the unit 2, a pipe 22 is provided, and this pipe terminatesin a nozzle 23 that sprays the liquid evenly over the filler in the unit2.

As heretofore stated, in acid preparation systems heretofore generallyused, extremely large absorption towers were deemed essen- ,ial, due '10the fact that the cold gas entering the system required a relativelylarge area of contact with the lime stone or the like, in order toobtain the required solvent action. In contradistinction to this, in mysystem, the acid in heated condition from the digestion plant, forexample, entering the system through the pipe 8, immediately exerts adissolving action on the lime stone or the like in the compartment 2,whereby the dissolving of the reaction material is accel rated.

'1 he gas entering the system through the pipe 14 may be either cold orheated, and if it is in heated condition, it will impart heat units tothe lime stone or the like, in the compartment 3, so that this limestone, upon contact with the liquor entering through pipe 18, will berapidly dissolved. The gas entering through the pipe 14 may comedirectly from a sulphur burner without cooling the gas in transit.

reacting material by heat units contained in the liquid or gasintroduced into the system, it will be manifest that such material maybe heated in any other way, for instance. by embedding heating coils insuch material within the tower.

A pressure valve 60 is preferably provided on the gas outlet pipe 13, inorder that the system may be maintained under any suit ablesuper-atmospheric pressure, if'desired. Of course, if the system isoperated under super-atmospheric pressure, the absorption action will befacilitated.

The system shown in Fig. 3 is similar in general respects to the systemshown in Fig.

While I have disclosed the heating of the 4,55 illustrated, that.

reeensfd 1', But, additional features: are incbnporated izn 3*. Forexample, each: unit; may be provided with an auxiliary chamber, as shownatQ'a, in; order thatitheauxiliary chamber may be hooked into thesystem, while its corresponding chamber is. being refilled with theFig.'.'3,.tlie liquid conduit 22. isipizouidedi with a suitable value;31, so. that the liquid may 51 be. fed: either to nozzle-23. orthnouglma pipe: 32 into. the: upper portion of the auxiliary unitQaz. Thetemperature: control or cooler 16 in form ofthe invention, may have itsinlet pipe 33: branched and: provided with a; valve 3 so; that; liquid;may be fed trons the unit 2 to; the: cooler, through: the inletfifi, orthrough the: inlet 36: t'romz the auxi-liiarychamber I In this:modification, the: pipe 119 will be provided. with suitable: ualwesafland'B/S, and with branch; PZlJPBST39 and 40; that lead to; the upper andlower portion of the chamber 2a; @btiously, whemthe: valves 37,38 areproperly set, gas: can flow front the unit 13 to 1'.directlmorihdiinectly by being by passed-athmughthe chamber 2014.;

To; this; modification, the hot strong acid inlet pipe 8 is .hsanchedaM1451 and; pro- I Midedi with: a suitable valveas to p ermit the hotstrong acid to; be fed lirectly into; the upper portion of either thechamber 2; or," 2a. From the above itm'ay bereadily seen that unit 2'can be kept'in operation while auxiliary unit 2a: loci "time" stone-orother suitablesubstance, and likewise, unit 261 may be usedasaaiatiliary means, while: chamber 2- is being refilled 1 It 7ismaiuziitest that aasimilkxr'marmer, gases or liqusi ds= may be; lay-passed. around any chamber Whilertherelilling processzis takingt'placeAs, anotheradditional: fiea-ture of the; em- V rbod iment shown in; Fig,3, I provide: atl the top or. the tower, a supplementary: absorptionchamber 3 which may: be; filled: with blocks; on the: liken Fresh: watermay enter this chamber through a pipe l, and fiimthe; chamloergit willmeet; the practically jexha'usted gases from: unit-l, which: risethrough: asupi'pe: 45;; The water com-pletesgthe ahsorption of anytraces of sulphurdioxide gas which may escape from chamber 1,; andcarries it vhack to; this," chamber! in solution, through a pipe 46which terminates in a rose 47 that sprays the liquid on to the filler ofthe unitl. v

Instead of intro the pipe 44, I may conduit a weak par relief liquorfrom sulphite digesters.

All chambers and conduits of the system should be lined with a suitableacidproof lining.

It is apparent ducing fresh water into introduce through this from theforegoing that the number of units may be varied from that theirpositioning likewise material 6;; As: i nv ng charged: with fresh tiallyprepared acidor mayhe varie spaced, as-welil suitablecopenzings or" ox-mayfl be." provided: as

gas; p 7 In: the operatiorrof. such: an organsizatibn, it may be takerias illustrated, hot: strong "acidfrom. a digester: 9 is; iiorced bya'pump "121 through theiline 8, and into; theunit, E2, and; is" sprayedzomto -the tiller .6 of that unit. Sulphuridioxidegas,suitahlyprepamedandcooled. to]: heatedflentets thelower' part-of unit 3; through-I4: and.passes upwardly in contact with the lime stone; filling; 6 for example,meetingi. coolz. acid: liquor: passing I through nozzle 1 8a: fromthecooler 16.- The d' they' be: horizontally as yerticallyrspaiced', andthat then conveying means I desired: for liquidor cooled'andtp artiallyexhausted gas-from; unit 3 is conveyed by the: pipe 19 into the lowerportion.'ozttherunitflz; s pliurousefacid, enterschamber 1,,through thenozzle 12, and meets this'partially exhausted gas in the presenceof'limestone',etc;. ,to form t a weak solution; This .latterleaves: unit,1 L'througli the pipe 22, and enters the unit 2 through no'zzl'e23; Inthe chambers2,.this'liqui'd1 intermingles with; products of thehot"strong acid from nozzle; and the combined liquid passes into thecooler'ldfor regulable adjustment of it's temperature'.,-j From 7 thecooler, it meets and viouslty described. s v r 'Obvio'uslyflf the systemof Figi 3ri'sz used "isteadfof that inFigc 1,; the actions'mentioned inconnection with: chamber 2 may'take I placefin the chamber 2a,

properly setto b'y-passth "2;. a In this arrangement, it is-o'f course,

rough 2a-and around feasi- "bl e toicond-uct, theygas firomyunit 3,,-directly to; unitlgwhile the'l'iquid' fromunit]; may,

atthesame time,.be divertedthrough chain--- cools the: 3, as re- 1 whenthevalvesare her 2a; Or botli'the gas and liquid paths 7 may bethLp-ennrits, adj

cent-ration; it also p unit ,.while a. mainiuni filler or beingrep'airedfurther" illustration of: the flexibility of this-system is: inutilizing: both units sired liquid. 4 q r .Iihave referred above''tousystmszin which the reacting material-i;6, the acid; enteringthrough 8, be heated, contemplate, w ii hotaci'dl can-not be drawn from:the: accumuand as a, further: -modifieation,.'I

rough unit 2a, Such flexibility ustment of liquid and gas con;

ermitsutili'zingf aLre l-ief t isbeinggcharged with 2" and';2,ywitllthe, de-

andigas entering'through I Linay Y hemconditions are such. that later oraccumulators Salt-o heat. suchv acid" by otherineans. For example; I.proposepto make additional provision'fior: heating: the sulphite liquorfromag sulphurtial l y finishedi co. 'be' located? in: a:

oled liquor: Sguehxliquor: may

by introducingjhot SOJ gases hurner'intoa: finished or partankconnectedby a valued bpi pe to-the conduit8,and.-the SOQgastfnom r a sulphurburner heated condition) may be inserted into thisf liquor;

{Ellis be PEG of particular advantage where the sulphite plants areperiodically shut down. For instance, in practically every. case, thesulphite plants are shut down on Sunday morning, and the cookingoperations are suspended until Sunday midnight, or Monday morning. Inthe event that cooking operations are suspended, as is usually the case,then there is no source from which to draw heat for the purpose ofheating up the necessary liquor with which to contact the filling in theacid making towers. However, the sulphur burners are usually startedsome three or four hours prior to the beginning of cooking, and in mypresent invention, I take advantage of this and lead a percentage of thehot S0 gases from the burners into a tank containing cool preparedsulphite liquor. After such liquor has been heated by the gases, it isintroduced into the tower for treating the filling 6.

Referring again to Fig. 3, it may be stated that the supplementary unitas not only completes the removal of sulphur dioxide from the gas, butprovides a liquid relatively high in sulphur dioxide, but relatively lowin base, to serve in the last gas reaction chamber 1, for betterreaction there.

It will be obvious that in operating either the system shown in Fig. l,or the system shown in Fig. 3, under super-atmospheric pressure, thatsuitable pressure valves must be arranged on the outlet pipes, and thatthe materials introduced must be forced into the tower under sufficientpressure to overcome the pressure maintained in the tower.

\Vhile specific embodiments of this invention have been presented forillustration, and as forms now considered preferable, no limitation isimplied thereby, but only such restrictions as are'imposed by the priorart under the terms of the claims herewith.

What is claimed and desired to be secured by Letters Patent is:

1. In the process of absorbing sulphur dioxide in aqueous solutions, thesteps which comprise reacting hot sulphurous acid solution with solidlime containing material, cool ing the resulting solution and passingsulphur dioxide gas therein in the presence of solid lime containingmaterial.

2. The process'as in claim 1 wherein the sulphur dioxide gas is hot.

3. In a process of absorbing sulphur dioxide in aqueous solutions, thestep which comprises passing sulphur dioxide gas into an aqueoussolution thereof in the presence of solid lime containing materialmaintained in heated condition.

4. In the process of absorbing sulphur dioxide in aqueous solutions, thesteps which comprise mixing hot strong sulphurous acid solution with acooler dilute sulphurous acid solution in the presence of solid limecontaining material, cooling the resulting solution, and passing sulphurdioxide gas therein in the presence of solid lime containing material.

5. The process as in claim 4: wherein the sulphur dioxide gas is hot.

6. In the process of preparing'a bisulphite liquor, the stepwhichcomprises mixing hot concentrated sulphurous acid solution with a coolerdilute solution of sulphurous acid in the presence of solid limecontaining material 1'5 and maintaining said material in contact withthe mixed solution for a time sufiicient for the material to reacttherewith.

7. The process of absorbing sulphur dioxide gas inaqueous solutions toobtain a Sill- '80 phite liquor, which comprises, mixing hot strongsulphurous acid solution with cooler dilute sulphurous acid solution inthe pres ence of solid lime containing material, cooling the resultingsolution, absorbing sulphur dioxide gas therein, in the presence ofsolid lime containing material, and passing unabsorbed sulphur dioxidegas from the last mentioned absorption into contact with water in thepresence of solid lime containing material 0 to prepare a dilutesulphurous acid solution to be mixed with further quantities of hotstrong sulphurous acid.

8. The process as in claim 7 in which the sulphur dioxide gas enteringthe first men- 135 tioned absorption stage is hot.

9. An apparatus for absorbing sulphur dioxide in aqueous solutioncomprising a tower divided into a plurality of separated absorptionunits, perforated plates in each of i00 said units said plates beingspaced from the bottom of each unit, means to pass sulphur dioxide gasinto the lowermost of said units beneath the perforated plate therein, abypass pipe to by-pass gas from the upper pertion of the lowermost unitaround the next adjacent unit and into a unit above the last mentionedunit, means to pass liquid through the units in series and cooling meansto cool liquids entering the lowermost unit from the unit next adjacentthereto.

10. In a process of absorbing sulphur dioxide in aqueous solutions, thestep which comprises passing hot sulphur dioxide'gas into an aqueoussolution thereof in the pres- 15 ence of solid lime containing materiahTHOMAS LEONIDAS DUNBAR.

